1. Field of the Invention
Exemplary embodiments of the present invention relate to a method of detecting touch positions and a touch position detection apparatus for performing the method. More particularly, exemplary embodiments of the present invention relate to a method of detecting touch positions capable of synchronously, e.g., simultaneously, recognizing a plurality of touch positions and a touch position detection apparatus for performing the method.
2. Description of the Related Art
Display devices capable of processing and displaying large amounts of information are being developed due to progression toward an information-oriented society.
To efficiently use electronic equipment, touch panels, which allow signals to be input through display surfaces of a display device without a separate input device such as a remote control, are becoming more widely used. For example, touch panels may be included on the display surfaces of electronic diaries, liquid crystal display (“LCD”) devices, e-readers, image display devices, and other similar devices.
As briefly discussed above, a touch panel is an input means capable of substituting for conventional input means such as a mouse or keyboard, specifically the typical touch panel is an information input means capable of allowing information to be directly input on a screen using physical contact, e.g., by a hand or a pen. A touch panel is considered to be an ideal information input means because it can be easily and intuitively operated. Recently, the touch panel has been employed in personal electronic equipment such as cellular phones, personal digital assistants (“PDAs”), and other similar devices, and is also used in commercial activities, e.g., by major companies such as banks and public offices.
Touch panels may be classified by their type of operation into capacitive type, resistive type, electromagnetic (“EM”) type, and other types of touch panels.
A basic concept of the capacitive-type touch panel is that a film having an electrode thereon is mounted on a liquid crystal panel and a voltage is applied to each corner of the film to generate a uniform electrical field in the electrode. When a finger or a conductive pen is touched on the electrode, a voltage drop is generated at the location of the finger or conductive pen, and that voltage drop is used to detect position coordinates of the touch location.
In addition, a basic concept of the typical resistive-type touch panel is that an upper transparent substrate having an upper electrode, displaying an image and providing a touch area, and a lower transparent substrate having a lower electrode and facing the upper transparent substrate occupy a predetermined space and are laminated. When the input means, such as a pen or finger, is touched at one position of the upper transparent substrate, the touch deforms one or both of the upper and lower substrates and the upper electrode in the upper transparent substrate and the lower electrode in the lower transparent substrate are contacted and apply an electrical current to each other via the contacting area. Accordingly, a voltage change according to a resistive value of the position is recognized, and detecting the position coordinates may be detected according to the voltage change in a control device of the touch panel.
Generally, the resistive-type touch panel is used as a touch panel input device recognizing the touch of a pen or finger. As described above, the resistive type recognizes a touch based on a surface resistance between the upper electrode and the lower electrode. When at least two touches are generated, e.g., when multiple contacts are made between the upper and lower substrates, a conventional resistive-type touch panel using whole plate electrodes as the upper electrode and the lower electrode may undesirably recognize an average electrical potential between the at least two touches rather than individually recognizing the multiple touches. Accordingly, a point in the middle of the at least two touches may be misrecognized as a touched position while the at least two touches may not be accurately recognized as multiple touched positions.